With the development of semiconductor technology, electronic products presently are increasingly tending to miniaturization with a light, thin, and compact design. In the field of electro-acoustic products, the microphone is a sensor that converts acoustic energy into electrical energy. A capacitive micro-electro-mechanical system (MEMS) microphone generally includes a vibration membrane (lower electrode) fixedly formed on a substrate and facing an opening disposed on a backside of the substrate, and a fixed plate (upper electrode) being suspended above the vibration membrane, and a cavity between the vibration membrane and the fixed plate. A capacitive MEMS microphone enables detection of a capacitive value change due to the displacement of the vibration membrane caused by a change in the acoustic pressure, and the detected capacitive value change is then converted to an electrical signal for processing.
A leakage current of a MEMS microphone can be measured by applying a voltage across the lower electrode and the upper electrode. Referring to FIG. 1, a voltage is applied between a first electrode plate (vibration membrane of the microphone) 101 and a second electrode plate (fixed plate) 102 of the capacitor to measure a leakage current. The smallest the leakage current, the better the insulation between the two plates, and the better the performance of the microphone.